Chemical mechanical polishing atomizing rinse system

ABSTRACT

A substrate polishing system includes a delivery arm having a nozzle configured to combine a rinse fluid and a gas into an atomized spray, and to direct the atomized spray toward a polishing pad. The atomization process causes droplets of the rinse agent in the atomized spray to become negatively charged. The negative charge causes in the rinse agent to adhere to waste particles and slurry, which facilitates removal thereof from the polishing pad.

BACKGROUND

[0001] 1. Technical Field

[0002] The present invention relates generally to semiconductor processing and more specifically to a rinse spray bar for use in chemical mechanical polishing of a semiconductor wafer.

[0003] 2. Background Information

[0004] Chemical mechanical polishing (CMP) processes are commonly used in the manufacture of integrated circuits to planarize wafer surfaces. One typical CMP system includes a polishing pad mounted on the upper surface of a planar platen. The polishing pad is wetted with chemically reactive, abrasive slurry. Commonly, the platen is rotated during the polishing process. The wafer is held by a wafer carrier, which typically is capable of transverse movement and also rotational movement about a shaft. The rotational and transverse movement of the wafer with respect to the polishing pad facilitates uniform CMP etch rates across the wafer surface.

[0005] During a CMP process, waste byproducts of the polishing process are generated. The nature of the deleterious waste products may include reacted chemical byproducts of the polishing process, degraded polishing pad components, and particulates from the abrasive component of the slurry.

[0006] One problem encountered in CMP is that the waste byproducts may coagulate and clog the grooves or other features on the pad, thereby reducing the effectiveness of the subsequent polishing steps and increasing the likelihood of defects. Accordingly, rinse arms have been incorporated into some CMP systems to deliver de-ionized water or other rinse agents to the pad to facilitate rinsing the waste byproducts from the surface of the pad.

[0007] One rinse arm, disclosed in U.S. Pat. No. 5,578,529, includes a rinse arm with spray nozzles positioned along its length to deliver a rinse agent at a pressure slightly higher than ambient to the surface of the pad. Another rinse assembly, disclosed in U.S. Pat. No. 5,738,574, combines a rinse line and one or more slurry delivery lines in a single fluid delivery arm which delivers the rinse agent and/or the slurry to the center of the pad. A third rinse assembly, disclosed in U.S. Pat. No. 6,280,299, includes a rinse agent delivery arm with sweeping nozzles along its length rotatably mounted adjacent the polishing pad. The sweeping nozzles urge the rinse agent and debris towards the edge of the polishing pad.

[0008] Each of these prior art rinse assemblies dispenses a liquid rinse agent to the polishing pad. The rinse agent acts to dilute, disperse and remove the waste byproducts. This rinse agent is usually either de-ionized water or ammonium hydroxide.

BRIEF SUMMARY

[0009] A substrate polishing system includes a substrate carrier, a polishing pad, and a delivery arm. The delivery arm has one or more nozzles configured to combine a rinse fluid and a gas into an atomized spray, and to direct the atomized spray toward the polishing pad. The delivery arm may include a manifold containing air and fluid delivery channels. A fluid deliver channel may receive the rinse fluid and deliver the rinse fluid to the one or more nozzles. A gas deliver channel may receive a gas, such as air, and deliver the gas to the one or more nozzles.

[0010] A method for polishing a substrate may include supporting a substrate above a polishing pad, dispensing slurry onto the polishing pad, and polishing the substrate against the polishing pad. Furthermore, the method may include atomizing a rinse fluid with a gas in a delivery arm, and directing the atomized rinse fluid toward the polishing pad. An effect of the atomization process may be electrically charging the rinse agent, which increases attraction between waste byproduct particles on the polishing pad and the rinse agent.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The invention can be better understood with reference to the following figures. The components in the figures are not necessarily to scale; emphasis is instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views.

[0012]FIG. 1 is a top view of a CMP system having an atomizing rinse system and a rotary polishing pad

[0013]FIG. 2 is a front view of the CMP system shown in FIG. 1.

[0014]FIG. 3 is a perspective view of a manifold of a rinse delivery arm.

[0015]FIG. 4 is a sectional view of the manifold shown in FIG. 3.

[0016]FIG. 5 is an exploded view of an atomizing rinse system.

[0017]FIG. 6 is a top view of a CMP system having an atomizing rinse system and a linear polishing pad.

[0018]FIG. 7 is a front view of the CMP system shown in FIG. 6.

[0019]FIG. 8 is a perspective view of a manifold of delivery arm shown in FIG. 6.

[0020]FIG. 9 is a sectional view of the manifold shown in FIG. 8.

[0021]FIG. 10 is an exploded view of the atomizing rinse system shown in FIG. 6.

DETAILED DESCRIPTION OF THE DRAWINGS AND PRESENTLY PREFERRED EMBODIMENTS

[0022]FIG. 1 is a top view of a first CMP system having an atomizing rinse system 100 disposed over a rotary polishing pad 10. A substrate carrier 12 for holding a wafer is disposed over the polishing pad 10, as is known in the art. The atomizing rinse system 100 includes a delivery arm 102 having a main portion 104 disposed outwardly from the edge of the pad and an extension portion 105 disposed near a center portion of the pad. The delivery arm 102 is generally straight, although it could also be curved or angled.

[0023] A plurality of atomizing nozzles 106 is disposed on the delivery arm 102 to deliver an atomized rinse agent to the polishing pad 10. The delivery arm 102 includes a manifold having a rinse agent delivery channel and a gas delivery channel (shown in FIGS. 3, 4, and 5).

[0024]FIG. 2 is a front view of the CMP system shown in FIG. 1. The delivery arm 102 is mounted to a bracket 20, which secures the delivery arm 102 above the polishing pad 10. The plurality of atomizing nozzles 106 is mounted to a lower surface of the delivery arm 102. The delivery arm 102 is mounted to the bracket 20 such that the lower surface of the delivery arm 102 is angled relative to the top surface of the polishing pad 10. By impacting the polishing pad 10 at an angle, rather than perpendicularly, the atomized rinse agent may more effectively dislodge waste byproducts from the polishing pad 10.

[0025]FIG. 3 is a perspective view of a manifold 110 of the main portion 104 of the delivery arm 102. The manifold 110 may comprise Polyethylene Terephthalate (PET), or another suitable material that does not erode when exposed to slurry. The manifold 110 has a side surface 122 and a lower surface 120, each extending between a first end surface 124 and a second end surface 125.

[0026] The side surface 122 defines a gas port 112 for introducing a gas into the manifold 110. The lower surface 120 defines a liquid port 114 for introducing a rinse agent into the manifold 110. Mounting ports 116 are disposed along the length of the lower surface 120. The second end surface 125 may define one or more threaded mounting holes 140 (shown in FIG. 5) for attaching the manifold 110 to the bracket 20. Alternatively, another type of fastener may be used for to mount the manifold 110 to the bracket 20.

[0027]FIG. 4 is a sectional view of the manifold 110 at 4-4. The manifold 110 defines a gas delivery channel 126 which extends from the gas port 114 to the first end surface 124. Each mounting port 116 includes an annular slot 128 that is in fluid communication with the gas delivery channel 126. The manifold 110 also defines a liquid delivery channel 134 which extends from the liquid port 114 to the first end surface 124. Each mounting port 116 includes a center passageway 130 that is in fluid communication with the liquid delivery channel 134. The center passageway 130 of each mounting port 116 may be threaded to accept the nozzle 106, which may also be threaded. Alternatively, each mounting port 116 may be configured for another method for mounting the nozzles 106.

[0028]FIG. 5 is an exploded view of the atomizing rinse system 100. The extension portion 105 of the delivery arm 102 includes a manifold 144. The manifold 144 includes a liquid port 148. The manifold 144 also includes a fluid delivery channel (not shown), and a gas port (not shown), and a mounting port (not shown), each of which is configured similarly to the corresponding items of the manifold 110. Like the manifold 110, the manifold 144 may be manufactured from PET or another material that does is not eroded by slurry.

[0029] The manifold 144 is coupled to the manifold 110 by a male nipple 142. One end of the male nipple 142 is inserted into the liquid port 148 of the manifold 144, and the other end of the male nipple 142 is inserted into the port 118 of the manifold 110 (shown in FIG. 3). The nozzles 106 are mounted at the mounting ports 116 of the manifold 110 and at the mounting port (not shown) of the manifold 144.

[0030] Each nozzle 106 may be a commercially available spray nozzle manufactured from PET or another material that does is not eroded by slurry. In the presently preferred embodiment, each nozzle 106 is part number 50471 available from Spraying Systems Company. Nozzle part number 50471 includes a PET spray set-up (part number SUF4B-PET), a PET retainer ring (part number CP9270-PET), and a Teflon gasket (part number CP3612-TEF).

[0031] Male connectors 150 and 156 are inserted into the gas port 114 of the manifold 110 and the gas port (not shown) of the manifold 144. A tee connector 160 is coupled to the male connector 150. A length of flexible tubing (not shown) couples tee connector 160 with male connector 156. A male elbow nipple 164 is inserted into the liquid port 112 of the manifold 110. A male plug 152 is inserted into the opening 154 (shown in FIG. 3). The opening 154 is a byproduct of manufacturing of the gas delivery channel 126, and is in fluid communication therewith. Alternatively, a manufacturing method may be used which does not create the opening 154, thereby eliminating the need for the male plug 152.

[0032] In operation, a gas enters the tee connector 160 and flows to the male connectors 150 and 156. In the manifold 110, the gas enters the gas port 114 and flows through the gas delivery channel 126 to each mounting port 116. The gas flows through the annular slot 128 of each mounting port 116, and into each nozzle 106. In a similar manner, the gas flows through the length of flexible tubing, into the manifold 144, and into the nozzle 106 attached thereto. A gas that has been found to work well in the atomizing rinse system 100 is clean, dry air. However, practically any non-corrosive gas may be used.

[0033] Simultaneously, a rinse agent is pumped into the rinse agent delivery channel 134 from one or more rinse agent sources using a diastolic pump or some other type of pump. The rinse agent enters the liquid port 112 and flows through the liquid delivery channel 134 to each mounting port 116 of the manifold 110, and to each nozzle 106 attached thereto. Furthermore, the rinse agent flows from the manifold 110 through the male nipple 142, through the manifold 144, and into the nozzle 106 attached thereto. A rinse agent that has been found to work well in the atomizing rinse system 100 is de-ionized water. However, other rinse agents, such as ammonium hydroxide, may be used.

[0034] The rinse agent and the gas are mixed in the plurality of nozzles 106 to form an atomized spray that is expelled from the nozzles 106. In an illustrative embodiment, the gas is delivered to the atomizing rinse system 100 pressurized to about 40 PSI, and the rinse agent is pressurized to about 30 PSI. However, these pressures are merely illustrative, and countless other pressure combinations may be used.

[0035] The atomization process causes droplets of rinse agent in the atomized spray to become negatively charged, and the nozzles 106 to become correspondingly positively charged. The negative charge on the droplets of rinse agent attracts the droplets to waste byproduct particles and slurry on the polishing pad 10. The negative charge causes in the rinse agent to adhere to the waste particles and slurry, which facilitates removal thereof from the polishing pad 10 and grooves in the polishing pad 10. Additionally, the negatively charged rinse agent attracts waste particles adhered to the wafer, and facilitates removal of waste particles from the wafer. Centrifugal force generated by the rotation of the polishing pad 10 causes the rinse agent and the waste particles and slurry to travel radially outward from the center of the polishing pad 10, and off of the polishing pad 10.

[0036]FIG. 6 is a top view of a second CMP system having an atomizing rinse system 200 adjacent to a linear polishing pad 202. The atomizing rinse system 200 includes a first delivery arm 204 and a second delivery arm 206. The delivery arms 204 and 206 are generally straight.

[0037]FIG. 7 is a front view of the CMP system shown in FIG. 6. As shown in FIG. 7, the delivery arms 204 are mounted below the polishing pad 202, and positioned so that a plurality of atomizing nozzles 106 expels an atomized spray onto the polishing pad 202. The positioning of the delivery arms 204 is not critical, and the invention may be practiced with one, two, or more delivery arms 204. However, the placement of one delivery arm at each lower turn of the polishing pad 202 as shown in FIG. 7 is preferred.

[0038]FIG. 8 is a perspective view of a manifold 210 of delivery arm 204. FIG. 9 is a sectional view of the manifold 210 at 9-9. Referring to FIGS. 8 and 9, the manifold 210 may be manufactured from PET, or another suitable material that does not erode when exposed to slurry. The manifold 210 includes the features of the manifold 110 discussed at length above, including a gas port 212, a gas delivery channel 226 a liquid port 214, a liquid delivery channel 234, and mounting ports 216. The gas delivery channel 226, the liquid delivery channel 234, and their relation to the mounting ports 216 are shown in FIG. 9.

[0039] An exploded view of the delivery arm 204 of the atomizing rinse system 200 is shown in FIG. 10. The delivery arm 204 operates in substantially the same manner as the delivery arm 102. The physical configuration is different to accommodate physical differences between the linear polishing pad 202 and the rotary polishing pad 10. Otherwise, the functionalities of the rinse systems 100 and 200 are identical.

[0040] Another embodiment of an atomizing rinse system may be constructed using an individual manifold for each spray nozzle 106, rather than a multi-ported manifold. Each manifold in such a configuration would be mounted to a suitable fixture to positing the manifold and the attached spray nozzle 106 adjacent to a polishing pad 10 or 202. Such individual manifolds are commercially available. For example, Spraying Systems Company produces a number of such manifolds. Such embodiment could be constructed almost completely from commercially available parts. However, the space occupied by the several additional lengths of flexible tubing, connectors, and the like, make this embodiment less desirable due to a limited space in most CMP systems. Nevertheless, this embodiment is contemplated as an embodiment of the claimed invention.

[0041] It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting, and that it be understood that it is the following claims, including all equivalents, that are intended to define the spirit and scope of this invention. 

We claim:
 1. A substrate polishing system, comprising: a substrate carrier; a polishing pad; and a delivery arm having a nozzle configured to combine a rinse fluid and a gas into an atomized spray, and to direct the atomized spray toward the polishing pad.
 2. The system of claim 1, further comprising a bracket coupled to the delivery arm for positioning the deliver arm adjacent to the polishing pad such that the atomized spray impacts the polishing pad at an angle between twenty and sixty degrees.
 3. The system of claim 1, wherein the delivery arm comprises a manifold containing delivery channels, the nozzle being coupled to the manifold delivery channels.
 4. The system of claim 1, wherein the delivery arm has a plurality of nozzles, each nozzle configured to combine a rinse fluid and a gas into an atomized spray, and to direct the atomized spray toward the polishing pad.
 5. The system of claim 3, wherein the manifold comprises a fluid deliver channel for receiving the rinse fluid and delivering the rinse fluid to the nozzle, and a gas deliver channel for receiving the gas and delivering the gas to the nozzle.
 6. The system of claim 3, wherein the manifold consists essentially of of polyethylene terephthalate.
 7. The system of claim 1, wherein the nozzle consists essentially of polyethylene terephthalate.
 8. A substrate polishing method, comprising the steps of: supporting a substrate above a polishing pad; dispensing slurry onto the polishing pad; polishing the substrate against the polishing pad; atomizing a rinse fluid with a gas in a delivery arm; and directing the atomized rinse fluid toward the polishing pad.
 9. The method of claim 8, wherein the step of atomizing the rinse fluid includes delivering pressurized rinse fluid to the delivery arm.
 10. The method of claim 8, wherein the step of atomizing the rinse fluid includes delivering gas to the delivery arm.
 11. The method of claim 10, wherein the step of delivering pressurized rinse fluid includes pressurizing the rinse fluid to between about twenty and forty PSI.
 12. The method of claim 8, wherein the step of atomizing the rinse fluid includes delivering pressurized gas to the delivery arm.
 13. The method of claim 12, wherein the step of delivering pressurized gas includes pressurizing the gas to between about thirty and fifty PSI.
 14. The method of claim 8, wherein the step of atomizing the rinse fluid includes delivering water the delivery arm.
 15. The method of claim 14, wherein the step of atomizing the rinse fluid includes de-ionizing the water.
 16. The method of claim 8, wherein the step of atomizing the rinse fluid includes delivering air to the delivery arm.
 17. The method of claim 8, wherein the step of polishing the substrate against the polishing pad includes polishing the substrate against a rotary polishing pad.
 18. The method of claim 8, wherein the step of polishing the substrate against the polishing pad includes polishing the substrate against a linear polishing pad.
 19. The method of claim 8, wherein the step of atomizing the rinse fluid includes atomizing the rinse fluid with the gas in a plurality of delivery arms.
 20. A substrate polishing system, comprising: a substrate carrier; a polishing pad; a means for combining a rinse fluid and a gas into an atomized spray; and a means for directing the atomized spray toward the polishing pad. 